The connexion between radioactive fall-out and the fission products was demonstarted by Blifford, Lockhart & Baus (1956), and the connexion between radioactive fall-out and radioactive strontium was reported by Libby also in 1956. Previous to the publication by Santholzer, Macků, Podrimek & Horak (1958) and Santholzer (1959) of records relating to the increased radioactive fall-out in areas in Central Europe (50° 10′ N. lat., 15° 50′ E. long.) which were not far distant from the area occupied by these University buildings, we had already decided to follow regularly the strontium 90 (90Sr) content of cow's milk produced in the area concerned.

Six strains of Str. pyogenes and four strains of Staph. aureus were found to grow well from large or small inocula in fresh human serum; four strains of E. coli failed to grow from large inocula and were killed when the inocula were small. Ps. pyocyanea, Proteus and Str. viridans sometimes grew and sometimes failed to grow in fresh serum.

In serum which had been treated with trypsin or heated at 56° C. for 1 hr. the Gram-negative bacilli grew readily, and growth was still better in serum which had been heated and then trypsinized. Heating at 56° C. and treatment with proteolytic enzymes were shown to destroy complement and to inactivate the bactericidal activity of fresh serum against a Shigella highly sensitive to the properdin system. It is suggested that these changes might be enough to explain the conversion of serum by proteolytic enzymes into a suitable medium for the growth of coliform bacilli. This change might be brought about by bacterial or leucocytic enzymes. Fibrinolytic serum from a cadaver was found to retain at least a part of its complement and bactericidal activity.

Strains of E. coli, Ps. pyocyanea, Proteus, Staph. aureus and Str. pyogenes were tested for growth in burn slough suspension and blister fluid. In slough suspension all strains grew well, but the Gram-negative bacilli grew rather more vigorously than the Gram-positive cocci. In blister fluid E. coli was killed and other strains grew.

These findings are discussed in relation to wound sepsis.

1. The average lethal dose of fluoracetamide for wild R. norvegicus was found to be 13 mg./kg. of body weight and the LD95, about 43 mg./kg.

2. Wild rats offered bait contatining 0·5, 1 and 2% fluoracetamide, after a period of conditioning, seemed to find it palatable and, on the average, ingested the equivalent of 18–100 LD50's. Warning symptoms appeared in about an hour or longer and included short convulsive spasms.

3. The speed of onset of warning symptoms leading to cessation of feeding was studied in albino rats dosed with the equivalent of 2 LD50's of sodium fluoracetate, zinc phosphide or fluoracetamide. Feeding ceased soonest in the case of sodium fluroacetate. Zinc phosphide gave very variable results, but it is thought that if wild rats had been used, feeding would have stopped nearly as soon as with sodium fluoracetate.

4. It is considered that field trials to compare the efficiency of 1% flouracetamide and 2·5% zinc phosphide, both with ‘prebaiting’, would be well justified.

5. Fluoracetamide at 2% may also prove to be a good alternative to 0·25% sodium fluoracetate as a ‘direct’ poison for controlling rats in sewers.

We are indebted to Miss Y. Larthe and Miss E. J. Taylor who took part in the bioassay and in one of the experiments with the marked rats.

During the period 1951–58, a study has been carried out of a series of seventeen families in which more than one member developed a staphylococcal lesion.

In eleven of these families, phage typing revealed that spread of infection from person to person had occurred. Once introduced into a household, the staphylococcus demonstrated great persistence; a particular strain could cause recurrent lesions in different members for as long as 6 years. The interval between the first and subsequent infection in another member of the same family was most irregular, but was usually 2–11 months.

The patient with recurrent furunculosis appeared to be mainly responsible for dissemination of strains.

In six out of the seventeen families, although multiple infections were encountered in the household, these were not due to case-to-case spread because more than one phage type of staphylococcus was isolated.

In one family investigated, there had been a dissemination of a hospital-acquired staphylococcus to another member of the household.

No infections were encountered in which the ‘epidemic strain’ 80/81 was responsible.

I wish to express my gratitude to Dr R. E. O. Williams of the Staphylococcal Reference Laboratory, Colindale, for his assistance in this work.

An easily prepared and readily reproducible culture medium for general use is described. A wide range of standard media can be prepared from it by simple modifications.

We should like to thank Mr P. D. Laverack and Mr D. Garwes for their exellent technical assistance, and Marmite Ltd. for much useful information about their product.

1. Children and their parents in a communal settlement (kibbutz) were followed for 14 months with special regard to the influences of streptococcal carrier rate, streptococcal infections, chemotherapy and heredity on the pattern of rheumatic heart disease.

2. Children with proven or probable heart disease showed the same streptococcal carrier rates as controls in spite of continued chemoprophylaxis with oral penicillin.

3. A single injection of penicillin, given to all kibbutz members on the same occasion, reduced the streptococcal carrier and infection rates to zero and maintained a marked drop for 3 months. Thereafter, the rates rose to higher levels than before. Courses of sulphamethoxypyridazine (‘Lederkyn’) given first to the total population and then to children only, caused only temporary interruption in the attack rate.

4. The prevalence of rheumatic heart disease in children of parents themselves affected was 2½ times greater than in controls exposed to the same environmental risks.

5. Affected children were more susceptible to streptococcal infections than controls with identical exposure.

Grateful thanks are due to Miss Pearl Weiskopf, B.Sc., for the statistical analysis. Without the close collaboration of Dr J. Yauluss, Nurses Tova and Ziva and the members of Kibbutz S this study would have been impossible. Thanks are also due to Lederle Laboratories Department of Cynamid International and their Israeli agent, Dr L. Goldshmidt, for the gift of ‘Lederkyn’, and to Mrs Rachel Kosh for help beyond the call of her secretarial duties.

1. When chick embryo cell monolayers were infected with ultrasonically treated elementary body suspension by a short period of adsorption some of the adsorbed virus lost infectivity in a few minutes. This was followed by a more gradual loss during incubation of the cultures. The lowest point was reached at 4–6 hr. followed by a rise in titre due to production of new virus at 7–8 hr. The quantitative assessment of these changes is discussed.

2. In such cultures, titration of intact and disintegrated cells after incubation for 4–5 hr., indicated an eclipse phase by showing an absence of infective virus in cells which ultimately produced it. The process of eclipse continued for several hours. With inoculum that had not been subjected to ultrasonic treatment it was not possible to show this by infecting HeLa cell monolayers.

3. Ultrasonically treated inoculum, compared with a similar, but untreated inoculum, had a three to flvefold higher titre. The virus units in it were more uniformly capable of infecting cells. After its adsorption to monolayers a rapid loss of some infective virus occurred within a few minutes which was not demonstrable with untreated inoculum. During incubation of monolayers infected with treated inoculum the loss of infectivity was faster, there was a more rapid production of new virus and a greater yield. The nature of the changes in the virus which were brought about by ultrasonic treatment have not been explained, but the use of such an inoculum markedly affected the results of experiments.

4. Treatment of infected monolayers with trypsin or EDTA caused the cells to shed as much as half their virus. This virus would not be released spontaneously into the medium or removed from monolayers by washing. This applied to all periods of incubation up to 24 hr. or more when marked increase of virus had occurred.

5. The disintegration of infected cells by ultrasonic treatment was efficient in releasing infective virus from them, although it was not possible to be certain all the virus in the cells was rendered detectable by this technique.

6. The effect of some technical procedures on the interpretation of results is discussed.

An investigation has been carried out over a period of 7 years of a series of eighty-one patients who first presented in 1951–52 with staphylococcal lesions. In seventy-two oases (89%) the infection was limited to a single, short episode of infection without recurrence. But nine patients (11%) developed recurrent lesions throughout the period. In these patients, from a comparison of the phage types isolated from successive infections, it was inferred that the organism had persisted in the body for over 6 years in two cases, for 4–5 years in five cases and for 1·3 years in three cases.

Nasal carriage also persisted for over 6 years in two cases and for 3–5 years in three cases.

In two cases, chronic skin carriage occurred in the absence of nasal carriage. There was persistence of staphylococci for 3 and 5 years in these cases, and the use of a special technique revealed that carriage in the deeper layers of the skin was particularly important.

The frequency distribution of phage patterns isolated in recurrent cases reflected the high incidence of Group II strains at the time when the strains were first acquired. New infections which arose in 1957–58 no longer showed this preponderance of Group II strains, as only eleven (28%) of thirty-eight new infections were caused by this group.

The bacteriological examinations were mostly carried out by the Central Public Health Laboratory, Colindale, and I wish to express my gratitude to Dr R. E. O. Williams of the Staphylococcal Reference Laboratory, for his assistance in this work. I am also grateful for the laboratory facilities afforded me by Dr Ridley at the Hospital for Tropical Diseases for the performance of the skin carriage testing.

1. Before undertaking a bacteriological survey of the waters of the Hooghly River and the associated canals a detailed epidemiological study over the past 20 years of cholera, as it affected the individual administrative wards of Calcutta, was undertaken. Sampling points were selected in accordance with the results of this study. Samples of water from the various points were collected at intervals extending from December 1958 to August 1959 in 2½–5 l. amounts. The whole sample in each case was filtered through special filter pads. The pads were first cultured in an enrichment medium from which plate cultures were subsequently made for colony isolation, serological and biochemical examination.

2. The sampling points on the canals were all adjacent to areas where the local endemicity was judged to be high; other points were by bathing ghats, etc. A total of eighty-nine samples covering all the sampling points were examined and Vibrio cholerae were isolated from twelve of these samples, eight of which came from twenty-six samples collected from two sampling points on the Chetla and Circular Canals, respectively.

3. The positive isolations were spread fairly evenly over the whole period of the study which covered both epidemic and non-epidemic periods including the monsoon. Although the incidence of cholera in Calcutta may fall to a low level during non-epidemic periods cases continue to occur throughout the year and the relationship of the maintenance of the infection in the city to the continuous potential infectivity of the open natural waters of Calcutta is discussed.

1. The reaction of slowly growing pathogenic bacteria with specific fluorescent antibody provided a means for their rapid identification.

2. Fluorescein isothiocyanate was used to label the globulins of antisera as it had a number of advantages over fluorescein isocyanate.

3. Several other isothiocyanates and a few sulphonyl chlorides tested were inferior to flurescein isothiocyanate as labelling agents. Some of the compounds caused protein precipitation, and others gave a less intense or less distinctive fluorescence than did dluorescein isothiocyanate.

4. The tests were performed by taking impressions of bacterial micro-colonies on glass cover-slips, drying and fixing the preparations, staining them with labelled antiserum, washing in saline and mounting in glycerol saline. The preparations were than examined microscopically under ultra-violet light.

5. Micro-colonies of Br. suis, Past. tularensis and Past. pestis, when treated with homologous labelled antiserum, fluoresced brightly under ultra-violet light and the individual bacteria were sharply defined and stained at the periphery.

6. Micro-colonies of these and other bacteria stained with normal labelled serum, or heterologous labelled antiserum, showed either very dim fluorescence under ultra-violet light, with poor definition of in dividual bacteria, or no fluorescence at all.

7. The technique described permitted specific identification of Br. suis, Past. pestis and Past. tularensis within 20 hr. of inoculation of agar plates with material suspected of containing one of these organisms.

This investigation arose out of a line of work suggested by Dr G. S. Wilson. We should like to thank Dr D. W. Henderson and Major L. H. Kent for providing facilities for the work, Mr E. O. Powell for continual encouragement and supervision of the microscopy, Dr D. W. Henderson, Dr M. C. Lancaster and Dr D. A. L. Davies for supplying antisera, and Mr T. W. Pearce for valuable technical assistance and the photographs.

The physical behaviour of aerosols atomized into stirred settling chambers, or into rotating drums, was examined by a radioactive tracer method and by a light scatter method. With suitable corrections, there was no difference between the two methods of measuring of physical decay. The tracer method is advantageous in that the data so obtained are on an absolute basis, whereas data from scattered light measurements are relative. The latter method, however, is less time consuming, provides an immediate notification of instrument performance and does not require that material be removed from the aerosol chamber for sampling purposes.

Eighteen volunteers were given live adenovirus attenuated by passage in pig kidney tissue culture. Thirteen were given adenovirus Type 7 and five were given adenovirus Type 4. All volunteers who were given Type 7 and who had no homologous neutralizing antibody on inoculation showed antibody rises. Except in one volunteer not in isolation no signficant symptoms were seen.

It is suggested that adenoviruses attenuated in this way might be useful for large-scale vaccination programmes.

1. The course of events following the feeding of salmonella-free pigs on food naturally contaminated with salmonellae has been followed. The pigs were killed at varying times after the commencement of the experiment and their organs examined for salmonellae.

2. None of the pigs showed any signs of ill-health and no pathological lesions were observed in them when they were killed. Salmonellae were found, however, in very small numbers in the mesenteric lymph nodes of some of them but not in any of their other internal organs or in their muscular tissue. The longer the pigs were fed on the contaminated food the more likely were their mesenteric lymph nodes to be infected.

3. Salmonellae were isolated from time to time from the faeces of the pigs but there was no suggestion of any of the pigs becoming permanent faecal excreters of these organisms.

4. Six pigs were retained for a short time after the use of the contaminated food was discontinued. Salmonellae were never found in their faeces and when they were killed the mesenteric lymph nodes of only one of them was found to be infected.

5. The results are discussed from the agricultural and public health viewpoints.

1. Heat labile and heat stable inactivating factors against T-system phages are present in normal guinea-pig and rabbit sera. These may be antibodies.

2. Sera of guinea-pigs immunized with phages T2, T3 and T4 contain heat labile and heat stable antibodies.

3. The heat labile activity is absorbed from guinea-pig serum by phage more readily than the heat stable activity.

4. Dilution of the sera reduces the heat labile activity more than the heat stable activity.

5. Complement has no effect on the inactivation or neutralization of phages T2, T3 and T4 by normal or immune guinea-pig sera.

Sixty-six paired sera from patients suffering from mumps were examined with Sendai and mumps virus particle antigen: 50% showed a rise of complementfixing antibodies to mumps virus particle antigen only and the rest to both antigens.

This relationship was further substantiated by the occurrence of both antibodies in a proportion of the sera of 362 blood transfusion donors and 978 sera from antenatal patients.

The occurrence of both antibodies in patients' sera is discussed and the conclusion is reached that one of the components of the mumps antigen complex is indistinguishable from the essential components of the Sendai virus.

I am indebted to the Maternity Department of the Edgware General Hospital for supplying the antenatal sera, and to Dr Preston of the Regional Transfusion Centre, Oxford, for the blood donor sera.

One of the major difficulties in determining the cleanliness of blankets for use in hospital wards is the estimation of bacterial contamination remaining on the blanket after washing. Present procedures are either cumbersome or not readily reproducible. Procedures for measuring bacterial contamination on fabrics may be based on dispersion of the bacteria as an aqueous or as an airborne cloud. As aerial sampling has the advantages that it may be rapid and simple and can be used to sample blankets which have been washed with a bactericide the possibilities of this principle were investigated. A simple method has been developed (Blowers & Wallace, 1955) in which the blanket is scraped manually by the edge of an agar plate so that the bacterial dust is thrown on to the exposed agar surface, but this procedure is difficult to control. There are wide differences in surface properties of blankets, and consequently in the amount of fibrous material shaved off by the Petri dishes. Puck, Robertson, Wise, Loosli & Lemon (1946) worked on the principle of hitting an area of taut blanket and sampling the aerial cloud so formed, but as their apparatus was not convenient for routine sampling in wards an improved version has been developed.

Part I

1. The following disinfectants were investigated for use in bar-soaps: Hexachlorophene (G11) (2:2′-dihydroxy-3:5:6:3′5′:6:′-hexachlorodiphenylmethane); Actamer (2:2′-thiobis, 4-6-dichlorophenol); DCMX (dichloro-m-xylenol); TMTD (3:4:5-tetramethyl thiuram disulphide); TCC (3:4:4′-trichlorcarbanilide); TBS (3:4′:5-tribromsalicylanilide) and TCS (3:3′:4′:5-tetrachlorsalicylanilide).

2. The concentration required for bacteriostasis of Staph. aureus was 2·5 p.p.m. for DCMX and 0·1 p.p.m. for TCS, the other disinfectants falling between these values. None were effective against E. coli, 12·5–50 p.p.m. being required for bacteriostasis (Tabel 1).

3. In the presence of serum the concentration required for bacteriostasis was increased (Table 4).

4. The soap inactivation coefficient (S.I.C.) is a value derived from zone diffusion tests. Zone diameters of the same disinfectant are compared in soap and soap-free solution so that the S.I.C. measures the effect of soap on disinfectant activity.

5. DCMX is inactivated by soap (S.I.C. = ∞). The activity of G 11 is much reduced by soap (S.I.C. = 200). Actamer and TMTD are active in soap, whereas TCC, TBS and particularly TCS is more active in soap than soap-free solution (S.I.C. = 0·32) (Table 3).

6. Another test based on zone diffusion is described which measures the effect of soap-soluble skin substances on disinfectant activity. Zone diameters of the same disinfectant are compared in fresh soap and used soap solutions.

7. Of the disinfectants tested only TMTD lost some of its activity in the presence of soap-soluble skin substances (Table 5).

Part II

8. Conventional bacteriological plate-counting technique was used to enumerate bacteria in wash-water. The bacteria were removed from hands by using a standardized washing procedure with bar-soap but without scrubbing.

9. Bacteria were not removed uniformly when washing was carried out twelve times in succession, significantly more bacteria being removed at the beginning of of the washing procedure.

10. When the same individuals were tested at weekly intervals the rate at which bacteria were removed in successive washes was found to vary significantly.

11. Using a single standardized wash the variation in the count of twenty individuals was followed for a period of 16 months. The count from one individual could vary by a factor of 10.

12. A design for a handwashing test, to take account of these variables is described. The bacterial counts of the wash-water when subjects used control soap for 1 week was compared with counts obtained from subjects using disinfectant soap. Subjects and soaps were randomized according to multiple Latin squares.

13. This handwashing technique was used to test the disinfectants described in Part I of this paper. All these disinfectants were effective but tetrachlorsalycilanilide (TCS) was the best. Soap containing 0·5% TCS caused an 84% reduction (Table 9).

The authors wish to thank Dr H. Wilkinson for the ideas he contributed and the interest he has shown in this work, and the Directors of Unilever Limited for permission to publish this paper.

Using a Dale organ bath and the ileum of passively sensitized guinea-pigs a specific sensitive reaction with as little as 1 μg./ml. of disintegrated whole cultures of various bacteria and 0·01 μg./ml. of purified Sh. dysenteriae and S. typhimurium polysaccharides was obtained.

More detailed study showed that 1 μg./ml. of Sh. dysenteriae degraded polysaccharide derived from the O antigen could be detected with consistency. Lower concentrations gave irregular results.

My thanks are due to the David Bruce Laboratory for supplying the antisera and the bacterial suspensions, to Prof. W. T. J. Morgan of the Lister Institute of Preventive Medicine for the antibody nitrogen determinations, to Dr D. A. L. Davies of the Microbiological Research Establishment, Porton, for the antigen preparations and to Corporals G. Willis and P. Brown, R.A.F., for much careful work in day to day experiments.

Suspensions and dried preparations of vaccinia virus were exposed to γ-rays in cobalt-60 sources. Suspensions completely inactivated by 6–8 × 105 rad. retained measurable immunogenicity. Dried preparations could not be completely in-activated even by doses of 11 × 106 rad., although the inactivation apparently followed first-order kinetics until about one particle in 107 survived, suggesting that the populations of vaccinia virus in the preparations were heterogeneous.

The development of the molluscum body and of the molluscum contagiosum virus is described. All cells of the molluscum lesion do not form molluscum bodies, but those which do probably show cytoplasmic abnormality prior to the appearance of virus particles within the cytoplasm. Such abnormal cells may reflect the activity of some infective precursor of the morphologically observable virus particle; they may alternatively represent cells which have successfully resisted invasion by the infective precursor.

Cells which have failed to resist invasion gradually become filled with virus particles and the nucleus becomes eccentric. The molluscum body thus formed is virtually a bag of virus particles, the wall of the bag being the peripheral cytoplasm, which seems to resist invasion and in which the nucleus remnant can readily be detected.

There appear to be two kinds of viruses. Development of the commoner virus is compared and contrasted with studies by Morgan and his colleagues of vaccinia and fowl pox. It is akin to fowl pox in its origin from foci of finely dispersed cytoplasm, here called cytoplasmic clouds; it is akin to vaccinia in that no evidence can be found of a denser, finely granular, pre-nucleoid material; it is like both in that the virus does not observably develop within the nucleus; and it is unlike both in that a nuclear change—the appearance of rather unspecific dense bodies—is seen. The structural changes seen in the virus particles during development are similar to those described by Morgan et al., but a slightly different interpretation is given of the behaviour of the transient ‘nucleoid’: they believe that it expands to form a central viroplasm, whereas in this paper it is believed to disperse through an already present central viroplasm.

The second type of virus is of uncertain origin. It may develop from, or at least it seems to be related to, a double-membrane structure seen in abnormal lesion cells.